ceil

SYNOPSIS
       #include <math.h>

       double ceil(double x);
       float ceilf(float x);
       long double ceill(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       ceilf(), ceill():
           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 ||
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
           or cc -std=c99

DESCRIPTION
       These  functions  return  the  smallest integral value that is not less
       than x.

       For example, ceil(0.5) is 1.0, and ceil(-0.5) is 0.0.

RETURN VALUE
       These functions return the ceiling of x.

       If x is integral, +0, -0, NaN, or infinite, x itself is returned.

ERRORS
       No errors occur.  POSIX.1-2001 documents a range error  for  overflows,
       but see NOTES.

ATTRIBUTES
       For   an   explanation   of   the  terms  used  in  this  section,  see
       attributes(7).

       +-------------------------+---------------+---------+
       |Interface                | Attribute     | Value   |
       +-------------------------+---------------+---------+
       |ceil(), ceilf(), ceill() | Thread safety | MT-Safe |
       +-------------------------+---------------+---------+
CONFORMING TO
       C99, POSIX.1-2001, POSIX.1-2008.

       The variant returning double also conforms to SVr4, 4.3BSD, C89.

NOTES
       SUSv2 and POSIX.1-2001 contain text about  overflow  (which  might  set
       errno  to ERANGE, or raise an FE_OVERFLOW exception).  In practice, the
       result cannot overflow on any current machine, so  this  error-handling
       stuff is just nonsense.  (More precisely, overflow can happen only when
       the maximum value of the exponent is smaller than the  number  of  man-
       tissa bits.  For the IEEE-754 standard 32-bit and 64-bit floating-point
       numbers the maximum value of the exponent is 128 (respectively,  1024),
       and the number of mantissa bits is 24 (respectively, 53).)
       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at
       http://www.kernel.org/doc/man-pages/.

                                  2015-04-19                           CEIL(3)
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